Extracting text blocks based on grep output

Question

I'm currently working with a text file that contains the following text blocks:

--------------------------------------
Beginning of block
Text
Random Text
keywordA
Text
End of block
--------------------------------------

--------------------------------------
Beginning of block
Text
Random Text
keywordA
Text
End of block
--------------------------------------

--------------------------------------
Beginning of block
Text
Random Text
keywordD
Text
End of block
--------------------------------------

--------------------------------------
Beginning of block
Text
Random Text
keywordd
Text
End of block
--------------------------------------

The objective is to have egrep detect certain keywords, and if those words exist, I would like to copy the block to another file. So, I'm currently searching with:

if egrep -wi 'keywordA|KeywordB|keywordC' Report
then
        echo "Words found!"

else
        echo "No words found!"
fi

I was wondering if there is any way to add a follow up action to use sed (for example) to copy the block of text where the words were found.

Expected output, in this example, would be:

--------------------------------------
Beginning of block
Text
Random Text
keywordA
Text
End of block
--------------------------------------

--------------------------------------
Beginning of block
Text
Random Text
keywordA
Text
End of block
--------------------------------------

The file "Report" contains dozens of blocks like this, but not all of them have the keyword. I would like to copy just the ones that do (as demonstrated in the above example).

Answer 1

it's so easy for magic awk command:

awk -v RS="--------------------------------------"
       '/keywordA/||/keywordB/||/keywordC/' RS='' infile.txt

You will get output as like below expected:

--------------------------------------
Beginning of block
Text
Random Text
keywordA
Text
End of block
--------------------------------------
--------------------------------------
Beginning of block
Text
Random Text
keywordA
Text
End of block
--------------------------------------

Answer 2

Maybe something along those lines will do:

awk '
    {
        if(/--------------------------------------/) {
            if(found)
                printf buffer
            buffer = ""
            found = 0
        } else
            buffer = buffer $0 "\n"
    }

    /keyworda|keywordb|whateveryouwant/ {
        found = 1
    }
' input_file.txt

Just adjust the keywords in the regexp near the end according to what you need. I store the lines in a variable, and when I reach a ----…---- line, if I encountered a wanted keyword, I print the content of this variable, then empty it and forget that I found an interesting keyword. I hope that's what you want. I can still edit it if needed, I guess.

This outputs interesting blocks to the standard output ; redirect the output to a file to copy them.